Cased glass and articles made therefrom



July28,1925. 1,547,715'

, 7 1 J.. R. BAKER I CASED GLASS AND ARTICLES MADE THEREFROM Filed Oct. 14,1922

'INVENTOR JAMES B. BAKER ATTORNEY' Patent ed 28 I umran STA mam-3am, annmeron, mew Jnnsmr; assr'enon 'ro wnsrm'enousn LAID A CORPORATION 01.

icas'nn emss m a'n'ncnns mun" I e mam fled October 14, 1922. a Serial No. 594,494.

To all it may com-em:

' and ing of glass,-

more readily worked and Be it known that I, JAMES Rain BAKER, a

citizen of the United States, and a resident of Arlington, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Cased Glass and Articles Made Therefrom, of which the following is a specification; a v

This invention relates to cased or com-' posite glass and articles made therefrom more particularly to a glass the inner surface of which is resistant to the action of alkali metals or the vapors thereof and the outer surface of which comprises glass of-a' usual composition. a An object of m invention is the formation of articles of g ass provided with linings chemically resistant to the action of alkali metals or their vapors. I

Another object of my invention is the manufacture of evacuated vessels containing alkali-metal vapor, for example, sodium-- vapor lamps, and comprising an inner coatsistant to the action of such vapor and an outer coating or base of a glass, sealed than glass resistant to such action. i

A further object of my invention is to facilita'te the working of glass, resistant to ing the same with a thelproduction of comp Suchglass .53.

as containers or. envelopesior devices emsilica. or other com the action of alkali-metal vapor, by formbaclcing or base of .ordinary silica glass having approximately the same coefiicient oi expansion as that of the alkali-metal-resistapt glass.

A still'further o 'ect of my invention is to articles of glass.

comprisingrean'inne'r coating of borate lass lass e from silica backed 1 wit or to iacilitate the workg ass.

app ed onsilicagl ing ofsuch borax be apparent upon reading the ollowing description; Ordinary glass, that-is, glass containing silica, as is well known, is readily attacked and other-alkali metals when such by sodium are heated in contact therewith. For .use

ploying alkali-metal vapor, in whole or in' part, or or'other purposes, it is esirable .to' make use of'glass free from pounds that become deby theaction of alkali-metals.

has developed and is the" subject matter of the application of A. H.

- difiiculties incidentto working and'sealingduction of what maybe termed a compos1 glass. Such glass may be prepared by conand. the other orfothersiof whichmay be ordinary glass, that. is,"'glass having-a sub- 'ferent kinds have'substantially the same coeflicient of exduring)- pipe and this ball then covered with another Compton, Serial No. 417,378, filed octets oxides of sodium, aluminumand calcium,

position, and is suitable for resisting the is a true glass, although one of unusual comaction of sodium and the other alkali metals or their'vapors but is not ve' easily worked and is, therefore,-

moreor ess 'diflieult to manufacture into sealed-invessels or the like, for such devices as may use sodium or other alkali metals as their source of light or for other purposes, involving the heating of such metals in contact with :theglass.

According to my invention, 1 obviate the in alkali-metalsresistant glass by the prosolidating together 'two or more layers, laminations, sheets, tubesor other portions of glass of a which isa glass, such asborate glass,'wh1chis resistant to the actionof the alkali metalsstantial proportion of sllica therein; If more than two layers are used, a layer of glass of one kind, preferably alternates with: that of another, for example, a plate of brdina silica-glass maybe coated on both sides wi alkalinetal-resistant' glass. In making such composite, glass 7 0 glass consolidated together vpansion to avoid "strains due to changes in fthetemperature of such glass, 'but'the melting and softemng t may be,'and pre i r'a ly are,.higher than that. oftheborateglass.

Any suitab e-method may beused for romy composite glass, for "camp 0, a small all of sodium-resistant glass ma be gathered on the end ofa glass-b ower s b owoints' of the silica glass 'glaefiiorexam' e, a lead orlime lass of approximately-t e samecoeficiento e ansion as that of the sodium-resistant g ass.

Such a of sodium-resistant glass, In.

may then be drawn or blown any dedesired shape, at'least' one of I it is preferable that the difsired form. If prepared in tubular or bulbous forms, the inner surface will naturally be composed of such sodium-resistant glass and the'outer surface will comprise the glass a plied thereto, for example, the lime or lead g ass used.

If the alkali-metal-resistant glass, as well as the other glass with which the resistant glass is to be incorporated, are available in illustrating one embodiment thereof and in which,

Fig. 1 is a side elevation, partly in sec tion, of a tube of alkali-metal-resistant glass surrounded by a tube of silica glass;

Fig. 2 is a side elevation, partly in section, of said glasstubes after the same have been heated, consolidated and blown into bulbular form; and,

Fig. 3 is a side elevation, partly broken away and partly in section, of a metallic vapor lamp, which may contain alkali metal vapor during the operation thereof.

The tube 3 (Fig. 1) may be composed of borate glass, or glass resistant to the action of the alkali metals, of any desired composition, for example, comprising the followin materials in the indicated proportions y weight. v

' Per cent.

Sodium oxide about 13 Aluminumoxide about 15 Calcium oxide about, 12 Boron oxide; n about Although the above roportions are stated as an example, it is o vious that the exact proportions are not essential, as the main idea is that the glass will be free from silica or other oxide reducible by the alkali metals and the usual silica content in glass is therefore replaced by an 'oxide, such as that of boron. It is obvious that substitutlons may be made in the above formula, as well as changes in the roportions of the constituents. For examp e, sodium oxide may be replaced by, or have in addition thereto, an oxide or oxides of other alkali metals. Likewise, calcium oxide may be replaced by or have added thereto, an oxide or oxides of other alkaline-earth metals. The oxides of magnesium, thorium, zirconium and the like, may also be employed as constituents of the borate glass.

' .Tube 3 may be surrounded by tube 4,

.which sis preferably only slightly larger and Corning lime glass, althou h it is I obvious that any glass may be use having approximately the same coefficient of expansion as the glass of tube 3.

These tubes, in the position shown in Fig. 1, may then be heated, as by the action of glass-blowers bench fires thereon, and blown or drawn to the desired form. The tubes are first heated to cause them to soften sufliciently, so that tube.3 may. be blown out against tube 4, to be consolidated there with and both may then be blown to any desired shape such, for example, as the bulbous shape 5, shown in Fi 2. The tube adjacent to one end of the be drawn out and tipped off at 6, leaving the bulb 5 with its neck? and, extending therefrom, the separate tubes 3' and 4.

The tubes 3 and 4 may be broken. off beyond the point 8 where such tubes become consolidated or welded together. The bulb 5, with its neck 7, will comprise an inner wall 9 of borate glass and an outer wall ulb may then 11 of lead, lime or other, desired glass, which preferably contains silica. Suchbulb may be used for sodium-vapor devices or any devices containing an alkali metal. Although only a simple form is shown in the drawing, it is obvious that composite glass, according to my invention, may be prepared in various forms of any desired size.

A lamp may be constructed with an envelope, such as shown in Fig. '2, with the inner wall of .borate glass. Such lamp; is illustrated complete, as to essentials, in ig 3. When the lamp is evacuated and sealed in, which latter operation is rendered easier because of the outer wall of glass containing silica, the inner portion or wall of such bulb is protected from the action of moisture and thereby prevented from possible deterioration.

In greater detail, the lamp illustrated in Fig. 3, may comprise a tubular glass container 12 consisting of an inner wall 13 of glass resistant to the action of alkali metals and an outer wall 14 of any desired kind of silica glass having a coefficient of expansion practically the same as that of the glass composing the wall 13, consolidated therewith according to my invention. A positive electrode for the lamp is shown at 15 and may consist of iron, tungsten or any refractory conducting material not aifected by alkali metals. The negative electrode 16, in this. instance, may consist of sodium or an alloy or mixture of sodium withanother or much longer time without deterioration than mel' if the same glass. a

Although I have shown a conventional form of tube, it is obvious that any desired form may be employed for myalkali-metal were constructed of an ordinary vapor-lamp;' for example, one of the formsdisclosed in Patent No. 1,076,058 to Podszus, October 21,. 1913 or that form disclosed inv Patent No. 1,200,770 to Skaupy, October 10, 1916.

Instead of forming composite glass articles as heretofore described, the same may be made by the usual process which is used in making articles of cased glass, such as by blowing a ball of alkali-metal-resistant glass covered with another glass of the same coeflicient of expansion and having a higher point, into the desired form. More in detail, such method may comprise athering a small ball of borate glass on t e end of a glass-blowers blowpipe, allowing this ball to. harden slightly, dippin the same into a pot of mel position and blowing the coated ball to the desired size and shape.

It should be un erstood that, wherever the term sodium or alkali metal is employed, the vapors thereof are also included, as well as the same in a heated or melted condition.

Although I have described what-I new glass of the esired comi consider the preferred embodiment of my invention, it is to be understood that modifications may sug est themselves to those skilled in the art w1thin the spirit and scope of the appended claims. What is claimed is:

-1. Composite glass comprising a coating" of a material resistant to the chemical action of alkali metals and vapors thereof.

2.- Composite glass comprising two laminatiohs of different kinds of glass consolidated together, one of said laminations being resistant to the chemical action of alkah metals. H 3. Composite (glass comprising silica glass on oneside an side. o

4. Composite glass comprising a consolidation of walls or layers of a pluralityof glasses, one of which is a borate glass, free from silica. V t 5. A. vessel or the like comprisingan inner coating of a glass resistant to the action of alkali metals.

6. A vessel or the like adapted to be evacuated for use as an enclosure for an alkalimetal vapor-device and comprising an outer portion of silica glass and an inner coating of borate glass.

7. A vessel or the like the walls of which comprise a consolidation of a layer of glass resistant to the action of the alkali metals and a layer of glass of a higher melting point; i

8. A vessel or the like comprising silica giass coated .on the interior thereof with rate g'lass. 9. A vessel resistant glass and silica-glass.

In testlmony whereof, I have hereunto subscribed my name this'thirteenth day of October 1922.

JAMES REID BAKER.

borate glass on the other 7 or the like comprisin a coni 'solidation of alternate layers of alka '-metal- 

